1. Field of the Invention
The present invention relates to a tire having an excellent withstand-voltage property, and more particularly relates to a tire having an excellent withstand-voltage property, which has a tread consisting of a rubber composition comprising a rubber and a specifically limited softening agent and a specifically limited carbon black.
2. Description of the Prior Art
Recently, a pneumatic tire is provided to special vehicles, such as vehicles for subway, monorail and the like, in view of noise and ride feeling, and it is well known that the use of such tire is effective.
These special vehicles are driven by an electric power source having a relatively high voltage, and therefore a high voltage is impressed upon the tire, and due to leakage current the tire is eventually damaged and burnt.
In order to solve these drawbacks, there have hitherto been proposed methods for preventing the electrification of tire. In these methods, a tire is made of a conductive rubber composition containing a conductive substance, or a conductive substance, such as metal wire or the like, is embedded in a tire so that the conductive substance is exposed to the tread surface, whereby the conductivity of the tire is improved and the electrification of the tire is prevented by the grounding action of the tire. The use of a tire formed of such conductive rubber composition or of a rubber composition having such conductive substance embedded therein ensures an electric discharge from the charged tire, but deteriorates the wear resistance, ride feeling and other important properties of the tire. Therefore, it has been very difficult to produce a tire suitable for practical use by the above described methods.